Front panels are disposed in liquid crystal displays for the purpose of protecting liquid crystal panels, etc. Examples of materials for use in conventional front panels for liquid crystal displays include (meth)acrylic resins typified by polymethyl methacrylate (PMMA).
In recent years, front panels having sheets made of polycarbonate resins have also been used because of having high impact resistance, heat resistance, secondary workability, lightness and transparency, etc. Particularly, a front panel for liquid crystal displays that has a hard coat on a multilayer sheet having an acrylic resin laminated on the surface layer of a polycarbonate resin sheet has been adopted to a wide range of front panels for liquid crystal displays, because of having excellent impact resistance, heat resistance, workability and transparency of the polycarbonate resins while having surface hardness and abrasion resistance comparable to conventional acrylic resins with a hard coat (see, for example, Patent Document 1).
The front panel for liquid crystal displays having the polycarbonate resin sheet is generally formed by a melt extrusion method, together with the acrylic resin.
In liquid crystal displays, an optical laminate for antireflection is generally disposed on an outermost surface. Such an optical laminate for antireflection suppresses image reflection or reduces reflectance by light scattering or interference.
An anti-glare film provided with an anti-glare layer having an irregular shape on the surface of a transparent base material is known as one of the optical laminates for antireflection. This anti-glare film can scatter outside light by the irregular shape of the surface and thereby prevent visibility from being reduced due to outside light reflection or image reflection. Also, this optical laminate is required to be provided with hard coat properties so as not to be damaged upon handling, because the optical laminate is usually placed on the outermost surface of a liquid crystal display.
The anti-glare film is required to have anti-glare properties and additionally desired to exert favorable contrast when located on the surface of a liquid crystal display, and to prevent so-called “glare”, which reduces visibility due to a brightness distribution resulting from the interference of the surface irregular shape of the anti-glare film with liquid crystal display pixels, when located on the surface of a liquid crystal display.
In the case of using such a liquid crystal display for on-board purposes such as car navigation systems, the inside temperature of a car changes greatly from low to high temperatures in an environment so that the front panel is prone to be deformed due to shrinkage and expansion ascribable to thermal fluctuation, leading to problems such as the generation of squeak noise by deformation. Particularly, in recent years, high retardation drawn front panels have been used as measures against blackout by polarized sunglasses and are therefore more prone to be deformed.
A resin laminate of Patent Document 2 solves the problem of a resin laminate having an acrylic resin layer laminated on a polycarbonate resin layer, i.e., the occurrence of protruding warpage in the acrylic resin layer due to a large dimensional change after moisture absorption between the laminated resin layers. However, the resin laminate of Patent Document 2 still has insufficient resistance to warpage deformation in a temperature environment exceeding 40° C. The temperatures of on-board displays may rise significantly beyond room temperature. Resin plates for use as protective plates for on-board displays are desired to be excellent in resistance to warpage deformation after being exposed to a severe high temperature and high humidity environment such as a high temperature environment exceeding 40° C., for example, an environment having a temperature of 85° C. and a humidity of 85%.
As mentioned above, front panels for on-board liquid crystal displays are required to be provided with various functions such as measures against blackout, anti-glare properties of preventing glare, and prevention of scratches and further required to resist a severe environment such as the inside of cars. Nonetheless, any front panel has not satisfied all of these requirements.